refactor: 功能按钮全面布局优化 — 均布四周+平行四边形样式+互斥合并

- 起立/趴下合并为切换按钮，移至左上角
- 模式选择器（3个互斥无缝隙）移至左上角最上方
- 步态切换（4个互斥无缝隙）移至模式选择器下方，仅普通模式可点击
- 照明/休眠/充电移至右上角，紧凑排列
- 所有功能按钮使用平行四边形形状（左侧向右倾斜，右侧向左倾斜）
- 底部控制区移除更多展开区域，仅保留摇杆
- 所有控制按钮未连接时灰色不可点击

Generated by Mistral Vibe.
Co-Authored-By: Mistral Vibe <vibe@mistral.ai>

app/src/main/java/com/example/m20_gamepad/ui/MainScreen.kt

@@ -17,10 +17,8 @@ import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.layout.width
 import androidx.compose.foundation.layout.windowInsetsPadding
-import androidx.compose.foundation.rememberScrollState
 import androidx.compose.foundation.shape.CircleShape
 import androidx.compose.foundation.shape.RoundedCornerShape
-import androidx.compose.foundation.verticalScroll
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.Info
 import androidx.compose.material.icons.filled.Settings
@@ -40,12 +38,19 @@ import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.geometry.Size
 import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.Outline
+import androidx.compose.ui.graphics.Path
+import androidx.compose.ui.graphics.Shape
 import androidx.compose.ui.layout.ContentScale
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.res.painterResource
 import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.unit.dp
+import androidx.compose.ui.unit.Density
+import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.LayoutDirection
 import androidx.compose.ui.unit.sp
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import androidx.lifecycle.viewmodel.compose.viewModel
@@ -66,6 +71,38 @@ import com.example.m20_gamepad.video.RtspVideoPlayer
 private val OverlayBg = Color(0x88000000)
 private val OverlayText = Color.White
 
+/** 平行四边形形状，用于功能按钮。skewLeft=true → 左下-右上斜边（左侧按钮）；
+ *  skewLeft=false → 左上-右下斜边（右侧按钮）。 */
+private class ParallelogramShape(
+    private val skewDp: Dp = 10.dp,
+    private val skewLeft: Boolean = true
+) : Shape {
+    override fun createOutline(
+        size: Size,
+        layoutDirection: LayoutDirection,
+        density: Density
+    ): Outline {
+        val skewPx = with(density) { skewDp.toPx() }
+        val path = Path().apply {
+            if (skewLeft) {
+                // 左下 → 右上 斜边（平行四边形向右倾斜）
+                moveTo(skewPx, 0f)
+                lineTo(size.width, 0f)
+                lineTo(size.width - skewPx, size.height)
+                lineTo(0f, size.height)
+            } else {
+                // 左上 → 右下 斜边（平行四边形向左倾斜）
+                moveTo(0f, 0f)
+                lineTo(size.width - skewPx, 0f)
+                lineTo(size.width, size.height)
+                lineTo(skewPx, size.height)
+            }
+            close()
+        }
+        return Outline.Generic(path)
+    }
+}
+
 /**
  * 主界面：RTSP 视频背景 + 双摇杆覆盖层 + 状态栏 + 控制按钮。
  *
@@ -144,12 +181,89 @@ fun MainScreen(
             modifier = Modifier.align(Alignment.TopCenter)
         )
 
+        // ---- 左上角控制区：模式选择 + 步态切换 + 起立/趴下 ----
+        Column(
+            modifier = Modifier
+                .align(Alignment.TopStart)
+                .padding(top = 56.dp, start = 12.dp),
+            verticalArrangement = Arrangement.spacedBy(6.dp)
+        ) {
+            ModeSelector(
+                currentMode = status?.basicStatus?.controlUsageMode ?: 0,
+                connected = connectionState == ProtocolClient.State.CONNECTED,
+                onSelectMode = { mode -> viewModel.sendSwitchMode(mode) }
+            )
+            // 步态切换——始终显示，仅普通模式 + RL 控制时可点击
+            GaitSelector(
+                currentGait = status?.basicStatus?.gait ?: 0,
+                enabled = connectionState == ProtocolClient.State.CONNECTED &&
+                        motionState == ControlCommands.MOTION_RL_CONTROL &&
+                        status?.basicStatus?.controlUsageMode == ControlCommands.MODE_NORMAL,
+                onSelectGait = { gait -> viewModel.sendSwitchGait(gait) }
+            )
+            StandToggleButton(
+                motionState = motionState,
+                connected = connectionState == ProtocolClient.State.CONNECTED,
+                onToggle = {
+                    if (motionState == ControlCommands.MOTION_IDLE ||
+                        motionState == ControlCommands.MOTION_LIE_DOWN
+                    ) {
+                        viewModel.sendMotionControl(ControlCommands.MOTION_STAND)
+                    } else {
+                        viewModel.sendMotionControl(ControlCommands.MOTION_LIE_DOWN)
+                    }
+                }
+            )
+        }
+
+        // ---- 右上角控制区：照明 + 休眠 + 充电 ----
+        Column(
+            modifier = Modifier
+                .align(Alignment.TopEnd)
+                .padding(top = 56.dp, end = 12.dp),
+            horizontalAlignment = Alignment.End,
+            verticalArrangement = Arrangement.spacedBy(6.dp)
+        ) {
+            // 照明：前灯+后灯，无缝隙
+            val frontOn = ledStatus?.front == 1
+            val backOn = ledStatus?.back == 1
+            Row(horizontalArrangement = Arrangement.spacedBy(0.dp)) {
+                LightToggleButton(
+                    text = "前灯",
+                    isOn = frontOn,
+                    enabled = connectionState == ProtocolClient.State.CONNECTED
+                ) {
+                    viewModel.sendLightControl(if (frontOn) 0 else 1, ledStatus?.back ?: 0)
+                }
+                LightToggleButton(
+                    text = "后灯",
+                    isOn = backOn,
+                    enabled = connectionState == ProtocolClient.State.CONNECTED
+                ) {
+                    viewModel.sendLightControl(ledStatus?.front ?: 0, if (backOn) 0 else 1)
+                }
+            }
+            // 休眠/唤醒
+            val isSleeping = status?.basicStatus?.sleep == 1
+            SleepToggleButton(
+                isSleeping = isSleeping,
+                connected = connectionState == ProtocolClient.State.CONNECTED,
+                onToggle = { viewModel.sendSleepSettings(!isSleeping) }
+            )
+            // 充电/结束充电
+            val isCharging = status?.basicStatus?.charge == 1
+            ChargeToggleButton(
+                isCharging = isCharging,
+                connected = connectionState == ProtocolClient.State.CONNECTED,
+                onToggle = { viewModel.sendChargeControl(if (isCharging) 0 else 1) }
+            )
+        }
+
         // ---- 底部控制区 ----
         BottomControls(
             viewModel = viewModel,
             connectionState = connectionState,
             motionState = motionState,
-            ledStatus = ledStatus,
             modifier = Modifier
                 .align(Alignment.BottomCenter)
                 .windowInsetsPadding(WindowInsets.navigationBars)
@@ -336,7 +450,6 @@ private fun BottomControls(
     viewModel: MainViewModel,
     connectionState: ProtocolClient.State,
     motionState: Int,
-    ledStatus: LedStatus?,
     modifier: Modifier = Modifier
 ) {
     Row(
@@ -357,14 +470,6 @@ private fun BottomControls(
             }
         )
 
-        // 中间控制按钮组
-        ControlButtons(
-            viewModel = viewModel,
-            connectionState = connectionState,
-            motionState = motionState,
-            ledStatus = ledStatus
-        )
-
         // 右摇杆（Yaw 旋转）
         Joystick(
             modifier = Modifier.size(180.dp),
@@ -378,170 +483,6 @@ private fun BottomControls(
     }
 }
 
-@Composable
-private fun ControlButtons(
-    viewModel: MainViewModel,
-    connectionState: ProtocolClient.State,
-    motionState: Int,
-    ledStatus: LedStatus?
-) {
-    val connected = connectionState == ProtocolClient.State.CONNECTED
-    val isRlControl = motionState == ControlCommands.MOTION_RL_CONTROL
-    var showMore by remember { mutableStateOf(false) }
-    val scrollState = rememberScrollState()
-
-    Column(
-        horizontalAlignment = Alignment.CenterHorizontally,
-        verticalArrangement = Arrangement.spacedBy(6.dp),
-        modifier = Modifier
-            .verticalScroll(scrollState)
-            .padding(top = 4.dp, bottom = 4.dp)
-    ) {
-        // 运动状态转换
-        ControlButton(
-            "起立",
-            enabled = connected && (motionState == ControlCommands.MOTION_IDLE ||
-                    motionState == ControlCommands.MOTION_LIE_DOWN)
-        ) {
-            viewModel.sendMotionControl(ControlCommands.MOTION_STAND)
-        }
-        ControlButton(
-            "RL控制",
-            enabled = connected && motionState == ControlCommands.MOTION_STAND
-        ) {
-            viewModel.sendMotionControl(ControlCommands.MOTION_RL_CONTROL)
-        }
-        ControlButton(
-            "趴下",
-            enabled = connected && motionState != ControlCommands.MOTION_LIE_DOWN
-        ) {
-            viewModel.sendMotionControl(ControlCommands.MOTION_LIE_DOWN)
-        }
-
-        // 步态切换——仅 RL 控制
-        if (isRlControl) {
-            Row(horizontalArrangement = Arrangement.spacedBy(4.dp)) {
-                MiniButton("基础", enabled = isRlControl) {
-                    viewModel.sendSwitchGait(ControlCommands.GAIT_BASIC)
-                }
-                MiniButton("楼梯", enabled = isRlControl) {
-                    viewModel.sendSwitchGait(ControlCommands.GAIT_STAIRS)
-                }
-                MiniButton("平地敏捷", enabled = isRlControl) {
-                    viewModel.sendSwitchGait(ControlCommands.GAIT_FLAT_AGILE)
-                }
-            }
-            MiniButton("楼梯敏捷", enabled = isRlControl) {
-                viewModel.sendSwitchGait(ControlCommands.GAIT_STAIRS_AGILE)
-            }
-        }
-
-        // 更多/收起切换
-        if (connected) {
-            ControlButton(if (showMore) "收起" else "更多", enabled = connected) {
-                showMore = !showMore
-            }
-        }
-
-        // ---- 更多控制（可展开） ----
-        if (showMore) {
-            Separator()
-
-            // 使用模式
-            SectionLabel("使用模式")
-            Row(horizontalArrangement = Arrangement.spacedBy(4.dp)) {
-                MiniButton("常规") {
-                    viewModel.sendSwitchMode(ControlCommands.MODE_NORMAL)
-                }
-                MiniButton("导航") {
-                    viewModel.sendSwitchMode(ControlCommands.MODE_NAVIGATION)
-                }
-                MiniButton("辅助") {
-                    viewModel.sendSwitchMode(ControlCommands.MODE_ASSIST)
-                }
-            }
-            Spacer(Modifier.height(4.dp))
-
-            // 照明
-            SectionLabel("照明")
-            val frontOn = ledStatus?.front == 1
-            val backOn = ledStatus?.back == 1
-            Row(horizontalArrangement = Arrangement.spacedBy(4.dp)) {
-                LightToggleButton(
-                    text = "前灯",
-                    isOn = frontOn,
-                    enabled = connected
-                ) {
-                    viewModel.sendLightControl(if (frontOn) 0 else 1, ledStatus?.back ?: 0)
-                }
-                LightToggleButton(
-                    text = "后灯",
-                    isOn = backOn,
-                    enabled = connected
-                ) {
-                    viewModel.sendLightControl(ledStatus?.front ?: 0, if (backOn) 0 else 1)
-                }
-            }
-            Spacer(Modifier.height(4.dp))
-
-            // 充电
-            SectionLabel("充电")
-            Row(horizontalArrangement = Arrangement.spacedBy(4.dp)) {
-                MiniButton("开始充电") { viewModel.sendChargeControl(1) }
-                MiniButton("结束充电") { viewModel.sendChargeControl(0) }
-            }
-            Spacer(Modifier.height(4.dp))
-
-            // 休眠
-            SectionLabel("休眠")
-            Row(horizontalArrangement = Arrangement.spacedBy(4.dp)) {
-                MiniButton("进入休眠") { viewModel.sendSleepSettings(true) }
-                MiniButton("唤醒") { viewModel.sendSleepSettings(false) }
-            }
-        }
-    }
-}
-
-@Composable
-private fun ControlButton(
-    text: String,
-    enabled: Boolean = true,
-    onClick: () -> Unit
-) {
-    Button(
-        onClick = onClick,
-        enabled = enabled,
-        colors = ButtonDefaults.buttonColors(
-            containerColor = Color(0x66333333),
-            disabledContainerColor = Color(0x33222222)
-        ),
-        modifier = Modifier.width(110.dp)
-    ) {
-        Text(text, color = if (enabled) OverlayText else Color(0x88FFFFFF), fontWeight = FontWeight.Medium)
-    }
-}
-
-@Composable
-private fun MiniButton(text: String, enabled: Boolean = true, onClick: () -> Unit) {
-    Button(
-        onClick = onClick,
-        enabled = enabled,
-        colors = ButtonDefaults.buttonColors(
-            containerColor = Color(0x66333333),
-            disabledContainerColor = Color(0x33222222)
-        ),
-        contentPadding = ButtonDefaults.TextButtonContentPadding,
-        modifier = Modifier.height(32.dp)
-    ) {
-        Text(
-            text,
-            color = if (enabled) OverlayText else Color(0x88FFFFFF),
-            fontSize = 12.sp,
-            fontWeight = FontWeight.Normal
-        )
-    }
-}
-
 @Composable
 private fun LightToggleButton(
     text: String,
@@ -552,40 +493,205 @@ private fun LightToggleButton(
     Button(
         onClick = onClick,
         enabled = enabled,
+        shape = ParallelogramShape(skewLeft = false),
         colors = ButtonDefaults.buttonColors(
             containerColor = if (isOn) Color(0xCCFFC107) else Color(0x66333333),
             disabledContainerColor = Color(0x33222222)
         ),
-        modifier = Modifier.width(110.dp)
+        contentPadding = ButtonDefaults.TextButtonContentPadding,
+        modifier = Modifier.height(32.dp)
     ) {
         Text(
             "$text ${if (isOn) "开" else "关"}",
             color = if (enabled) OverlayText else Color(0x88FFFFFF),
+            fontSize = 12.sp,
             fontWeight = FontWeight.Medium
         )
     }
 }
 
 @Composable
-private fun SectionLabel(text: String) {
-    Text(
-        text,
-        color = Color(0xFFB0B0B0),
-        fontSize = 11.sp,
-        modifier = Modifier.fillMaxWidth()
-    )
+private fun StandToggleButton(
+    motionState: Int,
+    connected: Boolean,
+    onToggle: () -> Unit,
+    modifier: Modifier = Modifier
+) {
+    val isStanding = motionState == ControlCommands.MOTION_STAND ||
+            motionState == ControlCommands.MOTION_RL_CONTROL
+    Button(
+        onClick = onToggle,
+        enabled = connected,
+        shape = ParallelogramShape(skewLeft = true),
+        colors = ButtonDefaults.buttonColors(
+            containerColor = if (isStanding) Color(0xCCFFC107) else Color(0x66333333),
+            disabledContainerColor = Color(0x33222222)
+        ),
+        contentPadding = ButtonDefaults.TextButtonContentPadding,
+        modifier = modifier.height(32.dp)
+    ) {
+        Text(
+            text = if (isStanding) "趴下" else "起立",
+            color = if (connected) OverlayText else Color(0x88FFFFFF),
+            fontSize = 12.sp,
+            fontWeight = FontWeight.Medium
+        )
+    }
+}
+
+// ==================== 模式选择器（3个互斥无缝隙） ====================
+
+@Composable
+private fun ModeSelector(
+    currentMode: Int,
+    connected: Boolean,
+    onSelectMode: (Int) -> Unit,
+    modifier: Modifier = Modifier
+) {
+    Row(
+        modifier = modifier,
+        horizontalArrangement = Arrangement.spacedBy(4.dp)
+    ) {
+        ModeButton("常规", ControlCommands.MODE_NORMAL, currentMode, connected, onSelectMode)
+        ModeButton("导航", ControlCommands.MODE_NAVIGATION, currentMode, connected, onSelectMode)
+        ModeButton("辅助", ControlCommands.MODE_ASSIST, currentMode, connected, onSelectMode)
+    }
 }
 
 @Composable
-private fun Separator() {
-    Spacer(Modifier.height(2.dp))
-    Box(
-        modifier = Modifier
-            .width(80.dp)
-            .height(1.dp)
-            .background(Color(0x44FFFFFF))
-    )
-    Spacer(Modifier.height(2.dp))
+private fun ModeButton(
+    text: String,
+    mode: Int,
+    currentMode: Int,
+    connected: Boolean,
+    onClick: (Int) -> Unit
+) {
+    val isActive = currentMode == mode
+    Button(
+        onClick = { onClick(mode) },
+        enabled = connected,
+        shape = ParallelogramShape(skewLeft = true),
+        colors = ButtonDefaults.buttonColors(
+            containerColor = if (isActive) Color(0xCCFFC107) else Color(0x66333333),
+            disabledContainerColor = Color(0x33222222)
+        ),
+        contentPadding = ButtonDefaults.TextButtonContentPadding,
+        modifier = Modifier.height(32.dp)
+    ) {
+        Text(
+            text,
+            color = if (connected) OverlayText else Color(0x88FFFFFF),
+            fontSize = 12.sp,
+            fontWeight = if (isActive) FontWeight.Bold else FontWeight.Normal
+        )
+    }
+}
+
+// ==================== 步态切换（4个互斥无缝隙，仅普通模式可用） ====================
+
+@Composable
+private fun GaitSelector(
+    currentGait: Int,
+    enabled: Boolean,
+    onSelectGait: (Int) -> Unit,
+    modifier: Modifier = Modifier
+) {
+    Row(
+        modifier = modifier,
+        horizontalArrangement = Arrangement.spacedBy(4.dp)
+    ) {
+        GaitButton("基础", ControlCommands.GAIT_BASIC, currentGait, enabled, onSelectGait)
+        GaitButton("楼梯", ControlCommands.GAIT_STAIRS, currentGait, enabled, onSelectGait)
+        GaitButton("平地敏捷", ControlCommands.GAIT_FLAT_AGILE, currentGait, enabled, onSelectGait)
+        GaitButton("楼梯敏捷", ControlCommands.GAIT_STAIRS_AGILE, currentGait, enabled, onSelectGait)
+    }
+}
+
+@Composable
+private fun GaitButton(
+    text: String,
+    gait: Int,
+    currentGait: Int,
+    enabled: Boolean,
+    onClick: (Int) -> Unit
+) {
+    val isActive = currentGait == gait
+    Button(
+        onClick = { onClick(gait) },
+        enabled = enabled,
+        shape = ParallelogramShape(skewLeft = true),
+        colors = ButtonDefaults.buttonColors(
+            containerColor = if (isActive) Color(0xCCFFC107) else Color(0x66333333),
+            disabledContainerColor = Color(0x33222222)
+        ),
+        contentPadding = ButtonDefaults.TextButtonContentPadding,
+        modifier = Modifier.height(32.dp)
+    ) {
+        Text(
+            text,
+            color = if (enabled) OverlayText else Color(0x88FFFFFF),
+            fontSize = 12.sp,
+            fontWeight = if (isActive) FontWeight.Bold else FontWeight.Normal
+        )
+    }
+}
+
+// ==================== 休眠/唤醒切换 ====================
+
+@Composable
+private fun SleepToggleButton(
+    isSleeping: Boolean,
+    connected: Boolean,
+    onToggle: () -> Unit,
+    modifier: Modifier = Modifier
+) {
+    Button(
+        onClick = onToggle,
+        enabled = connected,
+        shape = ParallelogramShape(skewLeft = false),
+        colors = ButtonDefaults.buttonColors(
+            containerColor = if (isSleeping) Color(0xCCFFC107) else Color(0x66333333),
+            disabledContainerColor = Color(0x33222222)
+        ),
+        contentPadding = ButtonDefaults.TextButtonContentPadding,
+        modifier = modifier.height(32.dp)
+    ) {
+        Text(
+            text = if (isSleeping) "唤醒" else "休眠",
+            color = if (connected) OverlayText else Color(0x88FFFFFF),
+            fontSize = 12.sp,
+            fontWeight = FontWeight.Medium
+        )
+    }
+}
+
+// ==================== 充电/结束充电切换 ====================
+
+@Composable
+private fun ChargeToggleButton(
+    isCharging: Boolean,
+    connected: Boolean,
+    onToggle: () -> Unit,
+    modifier: Modifier = Modifier
+) {
+    Button(
+        onClick = onToggle,
+        enabled = connected,
+        shape = ParallelogramShape(skewLeft = false),
+        colors = ButtonDefaults.buttonColors(
+            containerColor = if (isCharging) Color(0xCCFFC107) else Color(0x66333333),
+            disabledContainerColor = Color(0x33222222)
+        ),
+        contentPadding = ButtonDefaults.TextButtonContentPadding,
+        modifier = modifier.height(32.dp)
+    ) {
+        Text(
+            text = if (isCharging) "充电中" else "充电",
+            color = if (connected) OverlayText else Color(0x88FFFFFF),
+            fontSize = 12.sp,
+            fontWeight = FontWeight.Medium
+        )
+    }
 }
 
 // ==================== 辅助函数 ====================